Releasable tool holder and operating means therefor



May 29, 1962 G. o. CONNER 3,036,319

RELEASABLE TOOL HOLDER AND OPERATING MEANS THEREFOR Original Filed March12, 1951 5 Sheets-Sheet 1 INVENTOR. GUY 0. GO NIVE'R May 29, 1962 G. o.CONNER 3,036,319

RELEASABLE TOOL HOLDER AND OPERATING MEANS THEREFOR Original Filed March12, 1951 5 .J 5 Sheets-Sheet 2 Fla. 2.

, INVENTOR. 6U) O. OONNER MM/W ATTORNEY May 29, 1962 G. o. CONNERRELEASABLE TOOL HOLDER AND OPERATING MEANS THEREFOR 5 Sheets-Sheet 3Original Filed March 12, 1951 '00) 0. com/v51? Arm/WW G. O. CONNER May29, 1962 RELEASABLE TOOL HOLDER AND OPERATING MEANS THEREFOR 5Sheets-Sheet 4 Original Filed March 12, 1951 wQ il1 INVENTOR.

GUY 0. CON/VET? yam y May 29, 1962 G. o. CONNER 3,036,319

RELEASABLE TOOL HOLDER AND OPERATING MEANS THEREFOR Original Filed March12, 1951 mwsmqzc aur a c-ONNER Arrows? United States Patent Ofifice3,036,319 Patented May 2 9, 1962 3,036,319 RELEASABLE TOOL HOLDER ANDOPERATING MEANS THEREFOR Guy 0. Conner, Cleveland, Ohio, assignor toRepublic Steel Corporation, Cleveland, Ohio, a corporation of New JerseyOriginai application Mar. 12, 1951, Ser. No. 215,131, now Patent No.2,828,492, dated Apr. 1, 1958. Divided and this application Mar. 25,1958, Ser. No. 723,865

13 Claims. (Cl. -134) This invention pertains to a tool holder and themechanism associated therewith by which a tool is operated. Theinvention is adapted to machine tools for forming metal and moreparticularly to a machine adapted for high speed performance of avariety of operations such as spinning, tapping, drilling or the like.The invention has particular utility in the tapping or threading ofnuts, and other operations similar to these. This application is adivision of my United States Patent No. 2,828,492, dated April 1, 1958,for Nut Tapping Machine Having Releasable Tap Holding Means to DischargeTapped Nuts Therefrom.

Current practice in the threading of nuts utilizes a machine in whichthe tapping tool is bent at the end opposite the working end and isloosely disposed in a complementary recess in the machine. Onto this thenuts are threaded, while the tap is prevented from rotating and is heldagainst longitudinal motion by the bent end. As ths nuts are finished,they slide along the tool, around the bent end and off into areceptacle. The cost of these taps is considerable, but other moreserious disadvantages are also present. Because of the looseness of thetool in its recess, it has heretofore been virtually impossible to get afit closer than Class 1 or 2 on a nut produced by such methods. Thedevice also is relatively slow and the finish on the threads poor,compared to that on the bolts onto which the nuts are to be threaded.

Many other devices have been proposed for this type of work. In some,the tap was driven in and then reversed to recover the tool. This wasexpensive both in time and in tool wear, since the tool passed throughthe workpiece twice for one operation. Other devices used a rotatinghead having a plurality of vertical spindles. In these, the tap would bedriven through the nut, drop into a cup and then be picked up again bythe spindle as the nut was moved out of the way. These, too, were notentirely satisfactory, partly because the tap could not be held tightlyenough to produce an accurate thread.

With the machine of my invention, most of the disadvantages of prior artmachines are avoided. In addition, great savings are possible. As anexample, a single machine having tool holding and operating mechanismaccording to my invention may be made to produce as many nuts in a giventime as from 10 to 20 of present day machines. Moreover, by such adevice, a single operator may tend each machine where under present dayconditions an operator customarily tends two machines. Thus, for a unitlabor cost, a machine built according to my invention will produce fromfive to ten times as many nuts. The total effect of these savings makespossible extremely fast production of the product of the machine at lowcost, both in direct cost of the product and in overhead.

In addition to lessened cost, the quality of the product is greatlyimproved. Where with present day machines nut threads having a fit ofClass 1 or 2 are ordinarily produced, and a Class 3 fit is rare; with myinvention, nuts of Class 4 fit may easily be produced, and Class 5 fitsare not uncommon. In order to achieve this sort of fit, it is obviousthat no tearing of metal nor looseness of parts can be allowed. Theseconditions also make possible a much better finish on the surface of thethreads with the resultant advantages of increased strength and ease ofthreading.

The tools are driven through the work blank by spindles Which are, inturn, governed by cams on the machine. These tools are short and arefirmly held at both ends while cutting the thread. The machine thereforeeliminates all play in the spindles, tools and the workpiece.

A more complete understanding of the device of the invention, and theinvention itself, may be had by reference to the fellowing descriptionand drawings which form a part of this specification.

In the drawings:

FIG. 1 is an enlarged sectional view of the spindle drive mechanismshown in my above-mentioned United States patent;

FIG. 2 is a sectional view on the vertical centerline of the tool holderwhich is the subject hereof;

FIG. 3 is an end-elevational view of the tool holder mounted as in FIG.2;

FIG. 4 is a fragmentary view similar to FIG. 2 showing the tool shank ina partly retracted position; and

FIGS. 5-12, inclusive, are progressive, partly diagrammatic, sectionalview showing the location of the spindles and tool holders at eightdifferent circumferential points in the travel of the spindles; each ofthe views being taken on a plane including the centerline of the spindleand the main shaft of a machine such as that in my abovementioned UnitedStates patent, the views each being turned upright for uniformity.

Briefly, my invention is intended for use in an automatic machine havingone or more horizontal spindles operated from a central shaft. Thespindles, in addition to being rotated about the central axis of themachine, revolve to drive a tool and are moved axially by a stationarycam or similar actuating mechanisms. The spindles are very accuratelyand firmly located to avoid misalignment or play. As shown in my UnitedStates Patent 2,828,492, the spindles are arranged around the centralaxis of the machine in two matched sets, each spindle having an axiallyaligned, matching spindle facing it from the opposite set. The toolholders are adapted to hold a tool very firmly yet are able to releasethe tool to be picked up by the opposite head. Cam operated rodsextending through the spindles provide positively operated means forpassing the tool from one head to another. The tool must be providedwith shanks at both ends of the thread cutting part for the heads tograsp in order for the tool to be passed in this manner.

As indicated in FIGS. 5-12, and as fully disclosed in my above-mentionedpatent, the center of the machine between the two spindles is occupiedby a work holding mechanism adapted to receive a workpiece for each pairof spindles. The work holder securely clamps the workpiece in a fixedposition determined by a pilot part of the forming tool and is thusaccurately located relative to the spindles. The work holder carries theworkpiece along in fixed relation to the spindles to a discharge pointwhere it is discharged positively from the work holder.

As fully disclosed in my aforesaid patent and as indicated in FIG. 5,the machine in which the tool holder and its operating mechanism hereinare embodied provides co-axial tool driving shafts 98 which are mountedin opposite ends of the machine. The shafts, at their spaced confrontingends, carry tool holding heads 124 such that the tool holding heads aredisposed at opposite faces of a rotating work holder 84. Theoperating'mechanism is supported on a single main drive shaft 32 whichis fully illustrated in FIG. 3 of my aforesaid patent and which is shownin part in FIG. 1 herein. Without delving into details of the threadingmachine per se, it will be sufficient to note that power is ultimatelydelivered to the main drive shaft 32. The main drive shaft is journalledin supporting standards 14 and 16 disposed along the length of themachine. The shaft 32 (FIG. 1) is journalled near its end in end bearing(not shown) in the outer walls of the standards 14 and also in near endbearings 36 in the inner walls thereof. Still further support isprovided approximately mid-way between the center of the shaft and bothends by near center bearings 38 mounted in the central stationarymembers 40. These latter members are bolted or otherwise suitablymounted on the inner walls of the standards 14 at both ends. Thus, eachhalf of the shaft is supported by four bearings, three of which areshown in FIG. 1. Firm support, such as this, is necessary, because theshaft is the sole upport for nearly all of the operating mechanism ofthe machine. Furthermore, such support will help to prevent whipping ofthe long shaft.

FIG. 1 discloses the mechanism for driving and controlling one tool atone side of the work holder. There are a plurality of tool drivingshafts mounted for operation in one end of the machine, and an equalpaired number in the other end. Identical mechanism is employed forcontrolling the several tool driving heads. Therefore, a description ofthe tool driving shaft of FIG. 1 and the mechanism associated therewithwill serve as a disclosure of the whole.

A large bull or sun gear 50 is keyed to the shaft 32 adjacent to andinboard of the near center bearings 38. This gear is the sun gear for aplanetary gear system formed by planetary pinion 52 and those of theother tool driving shafts of the set. These pinions are carried aboutthe sun gear 50 by an irregular shaped drum supported partly on theshaft by center bearings 54 and partly on the stationary members 40 byroller'bearings 56. This drum is driven through an internal ring gear'58, driven by a pinion which is not shown.

The ring gear 58 is mounted on an end plate 70 which also supports theroller bearings 56. The end plate 70 is connected to the rest of thedrum by a cover member 72 which may conveniently be bolted to the endplate 70 and to the spindle supporting member 74. The spindle supportingmember 74 is fastened to the inner wall member 76. Holes 78 may beprovided in the wall member 76 into which a bar may be inserted forturning the machine by hand, if desired. The wall member 76 holds thecenter bearings 54 and also helps to. support the drum. A center hub 80joins the wall members from both sides and completes the basic structureof the rotating drum. A second spindle support member 86 may be bolted,or otherwise fastened to the wall member 76, and a cover plate 88 maythe used to cover the complete end of the assembly. The cover 88 andspindle support 86 slide freely relative to a guide member 18.

As noted above, the eight spindles on each side are driven by themeshing engagement of the bull gear 50 withthe pinions 52 on thespindles (FIG. 1). Each of the spindles is adapted for longitudinal aswell as rotary motion, thus being adapted to carry driving heads whichdrive a tool in a rotary motion While feeding it through a nut blank,or. other Workpiecep and then following discharge of the finished nut,the heads carried by the spindles return the tool to its originalposition. it will be apparent that, while the shaft 32 is rotating inone direction, the spindle-carrying drum device will be driven in theopposite direction because of the internal gear drive at the ends of thedrum. Thus, the pinions 52 are carried around the bull gears 50 in aplanetary manner and consequently are driven at a comparatively highspeed. The pinions 52 may be formed as a part of the spindle 98 itselfor may be suitably fixed thereto. As best shown in FIG. 1, the spindle98 extends through four of the individual members of the rotating drum.At its right hand end inthat figure, the spindle is journalled in abronze bearing bushing 100 pressed into the support 7 member 86.Suitable packing 102 is provided between the cover 88 and the flange ofthe bushing to keep dirt and chips isolated from the bearings within thedrum member,

and to keep cutting fluid and the like within the bushing as will appearhereinafter.

The spindle 98 next passesthrough the end wall member 76. At this point,a hardenedsteel bushing 104 is pressed into the member. The surface ofthe spindle adjacent this bushing is also hardened. A form of ballbearing which will journal the shaft both for rotational andlongitudinal motion is provided in the space between the bushing and thespindle. This bearing is formed by a sleeve 106 made of brass or similarmaterial and into which two or more circumferential rows of balls 108are staked in holes formed therein. This assembly of balls and retaineris placed between the bushing 104 and the spindle shaft in that regionwhich then act as races for the ball bearing. It is evident that, inaddition to the rotary motion of a regular ball bearing, the spindle canmove longitudinally, rolling the balls 108 on the bushing 104 andcausing the retainer and ball assembly to move longitudinally one-halfthe distance moved by the spindle. The bearing is formed so that theballs are preloaded. That is, the diameters of the balls are slightlygreater than the space allowed for them between the bushing 10 4 and thespindle 98. This preload is preferably of the order of .0003 to .0005inch. A snap ring 110 may be provided for this bearing and may also beused for the others to hold standard oil seal rings in place if desired.

The second and third spindle bearings are similarly formed andpreloaded. The second bearing 112 is located in an inwardly extending,wide flange 114 formed in the spindle support member 74. This bearingalso includes a hardened bushing 116 pressed into an opening in theflange 114 as a race for the bearing. The third bearing 118 includm abushing 120 pressed into the end plate 70 and on which the bearing mayroll. A cover plate may be provided at this end to protect the bearingsand retain grease.

At its end nearest the center of the machine, each spin dle carries atool holding head 124 which will be de scribed in more detailhereinafter and with which this invention is mainly concerned. Thepinion 52 is located between the first and second bearings 106 and 112,and a follower block 126 with controls the longitudinal movement of thespindle is located between the second and third bearings. The spindlesare journalled in the follower block by two commercial angular contactball bearings 128, one at each end of the block. A fixed positon of thespindle relative to the block is maintained by engagement of one of thebearings with a shoulder 130 on the spindle against which the bearing isheld by the pressure of a nut 132 against the other bearing. This nut isthreaded on a threaded part 134 of the spindle shaft and is retained bya jam nut 136. A flanged washer 138 having portions bent over the flatsof the nuts to prevent relative rotation therebetween is located betweenthe nuts 132 and 136. The nut 132 may be partially bored out as shown toclear a shoulder 140 on the spindle.

The follower block 126 is an irregularly shaped block having anouter'surface of parti-cylindrical form. A sheet 144 of brass or bronzeor other bearing material covers this outer surface and is Wrappedaround the block having a tongue 146 extending between the two rollers148 on each block. The rollers 148 may be standard antifriction bearingsmounted on headed pins threaded or otherwise held in the block. They arespaced apart just far enough to straddle a cam ridge 150 formed on camsegment blocks 152 which are held in the stationary part 40 of thesupport for the machine. Thus, while the rollers straddle the cam ridge150, of this drum cam, they will translate any change in the location ofthat ridge "into longitudinal motion of the spindle. However, since thefollower block is free to rotate on the spindle, it is necessary to havesome means of holding it in a fixed position with the rollers engagingthe ridge. This is accomplished by the engagement of the outer surfaceof the brass sheet 144 with the inner surface of the cover member 72which is finished as a bearing surface for the follower blocks to slideon longitudinally. Because of their wide arcuate outer surface, theblocks are then restrained from turning about the spindles. Both thespindles 98 and the cover member 72 rotate about the center of themachine at the same speed. Therefore, the only motion between the cover72 and the follower block is the longitudinal sliding induced by thecam.

In FIGS. 2 and 3, the head 124 is shown enclosed in a housing formed oftwo similar pieces 156 and 158 bolted together and fixed to the coverplate 38. These pieces are formed with an accurately machined andhardened inner cylindrical surface. The outer surface 160 of the base162 of the head and of a portion of the front plate 164 are alsohardened and ground. A bearing assembly 166' similar to those providedfor the spindle in both formation and function is inserted in preloadedcondition between the head and the housing to provide additional supportfor the head. I The head is formed of three principal pieces: the base162, a retaining nut 168 and the front plate 164. These parts are heldtogether by square-headed bolts 170 engaged in an annular T-slot 172,formed by the base and retaining nut. The bolts 170 extend throughspaced holes in the front plate and are fastened by nuts 174. Theretaining nut 168 is screwed onto the end of the spindle and is formedwith holes 176 to receive a spanner wrench. A key 178 engaged betweenthe spindle and the base member 162 prevents relative rotationtherebetween. The front plate 164 is formed with a central opening 180shaped to fit the tool 154 which it is to carry (FIG. 3).

The tool 154 (FIG. 2) is formed with two shanks 182 and 184 on the endsof a thread c-utting portion 186. This thread cutting portion may befor-med as any thread cutting tap. The shanks also may be symmetricalbut preferably are formed as shown in the drawings. The tool, as viewedin FIG. 2, is initially supported by the right hand shank, while it isinserted through the workpiece, is then gripped by the other head on theleft hand shank. Both shanks are held during the cutting operation,after which it is carried solely by the left hand shank and is withdrawncompletely from the workpiece which is then discharged, after which thetool is passed back so that the right hand shank is picked up and heldas initially, th left hand shank being released. At the ends 188, theshanks are pointed to assure easy entry into the head. The left handshank 182 is formed in three different diameters; the first two beinguseful in holding and releasing the tool easily from the head as willappear later. The largest, 191), of the three diameters acts as a pilotdiameter to center the workpiece as the tool is inserted into the holein the center of the blank. This operation of the machine will also bedescribed in greater detail hereinafter. Since there is no need for apilot on the right hand shank 184 where the nut is discharged, thisshank is formed with only the two diameters. I

The head is formed with novel holding means for the tool which providesfor easy insertion and ejection of the tool while, at the same time,assuring a positive drive of the tool and the removal of any play fromthe grip. The drive of the tool is accomplished primarily by engagementof the shank 182 or 184 with the opening 180 in the head. The othercharacteristics are obtained from a loaded hearing arrangement formed inthe head by the following described means. A hardened bushing 192 ispressed into the front plate 164 at its center. At three equally spacedradii, pins 194 extend through openings in this bushing and the frontplate. Each of these pins is pressed toward the center by a spring 196engaged between a shouldered seat 198 and a plug 200. The spring, seatand plug are disposed in three equally spaced radial holes in the frontplate. As best shown in FIG. 3, the plug 260 is held in the head by twoscrews 202 extending into the front plate and engaging notches on bothsides of the plug.

- A retainer bushing 204, slidably disposed in an opening in the centerof the bushing 192, is provided with three elongated dimples 206 equallyspaced about its periphery. Centrally disposed in the dimple is provideda pin 208 having a near conical or chisel-pointed head to match thepoint of the pin 194. The pin 20% extends through and is slidable in ahole in the bushing 2114. Thus the pointed pins 194 act as detent pinson the bushing in two positions, one on each side of the pin 208. Inaddition to acting as a detent, the pin 194 holds the bushing andprevents it from rotating out of line with the tool and also transmitssome of the force of the spring 196 to the headed pin 208 urging it alsoin an inward direction against the shank 182 or 184 of the tool 154. Adimple 210 formed in the shank 182 at the proper location providessurfaces engaged by the pin 298 which acts as a detent and holds thetool in place in the head.

In each angular space between the pins 194, the bushing 204 is formed asa bearing retainer containing two balls 212. The diameter of these ballsis greater than the thickness of the bushing, thus allowing them toroll. When the tool 154 is in its inserted position (FIG. 2), the ballsare engaged in a loaded state between th lands of the shank of the tool,and the inner surface of an opening 214 in the bushing 264. Thus thetool is supported at two longitudinal points at each of threecircumferential locations. This support is very secure being obtained bythe deformation of a steel ball of approximately .0005 inch on thediameter, although this amount may be varied according to the size oftool used. These balls could'also press into the grooves or flutes. Thisis particularly true where three or two flutes are used. In such a case,the flutes could be stepped in a manner similar to the lands in thepreferred embodiment.

It will be noted that both the surface of the opening 214 and the landsof the shanks 182 and 184 are stepped, and that these steps are equal sothat the balls may he of the same diameter and be equally loaded. As thetool is ejected to the position shown in FIG. 4, the balls are rolled onthe bushing 192 by the movement of the tool, thus causing the retainer204 to move outwardly also. However, the tool does not have to roll outof engagement with both balls in the now. If that were required,movement of the tool and of the retainer 204 would be more than couldeasily be accommodated. Therefore, the stepped construction is used. Asillustrated in FIG. 4, after the tool has rolled a short distance, theballs 212 nearest the outer face of the head roll off a step 216 (FIG.4) on the shank of the tool. At the same time, the other balls arerolling off a step 218 in the inner surface of the bushing 284. Themagnitude of the steps is such that the tool is then released and isfree to pass out of the head. At this point, the retainer bushing 204has moved to the position where the spring-pressed pin 194 has passedover the head of the pin 208, and is thus in position to locate thebushing at its outer position. It will be recognized that by usingdifferent sized balls on the two (or more) longitudinal positions, onlyone of the pressure surfaces need he stepped to accomplish the desiredresult.

The tool is pushed out of the head by a rod 220 (FIGS. 1 and 2)extending through a central opening 222 in the spindle. The retainerbushing 294 has a hole 224 (FIG. 2) extending through it to receive therod which can therefore engage the end of the tool to push it. The rod224 is formed with a shoulder 226 adapted to engage the rear face 228 ofthe retainer to assure that it is moved to its outer position in placeto receive the tool when it is again picked up by the head.

Movement of the rod 220 is induced by a cam and follower arrangement atthe opposite end of the spindle from the head (FIG. 1). At this end, acollar 230 is formed on the rod to engage a small ball thrust bearing232 held in a follower member 234. The follower member is freelyjournalled on the end of the spindle 98, so that it is carried by thespindle, but leaves the spindle free to rotate while the follower may besliding longitudinally of the spindle. A.-roller 236 journalled in themember 234 engages a cam track 238 which extends into a slotted openingin the member 234. A spring 240' engaging the member 234 and the cover122urges the member 234 against the cam track 238, but in order toassure positive following by the follower, a radially extending roller242 may be used engaging the surface of a second cam track 244. Thetracks 238 and 244 may preferably be separate for ease of assembly.

In its operation, as explained heretofore, the machine in its preferredembodiment is driven with two motions. The shaft 32 carrying the bullgears Shrotates in a direction such that the top of the gears areapproaching the observer in all figures. The drum carrying the spindlesand work holding device rotates in the opposite direction.

In FIGS. -12, inclusive, are shown eight positions of the spindle as itpasses around the machine. These stations, however, are not stoppingpoints, for the rotation of the device is continuous. The operation ofthreading the nut may best be explained by a detailed reference to thesefigures. These figures are viewed from a longitudinally extending planethrough a single pair of spindles as they pass around the machine. Eachof the figures has been shown in an upright position, including thosewhich normally would have been inverted because they were taken at ornear the bottom of the machine. This was done so that comparisons of thefigures might be made more easily on uniformly positioned views.

In FIG. 5 which may be taken as the first station, the nut blank hasjust been injected into a work holding mechanism 84. A clamp 246 is heldopen by a cam formed on a support 248 and the tool. 154 is firmly heldin the right-hand head 124 which is substantially fully retracted by thecam on the segments 152. The right hand central rod 220 is alsoretracted as its follower 234 follows the right hand cam fully to theright. This position can be assumed to be approximately 330 degrees ofthe cycle. It will be noted that the left hand head 124 is located justslightly to the left of its completely extended position.

As the spindle moves from the first station to the second station (FIG.6), the left hand head moves slightly to pick up the tool. At the sametime, the right hand head moves quite rapidly to the left causing thetool to enter the hole in the nut blank. During this motion, the hole inthe blank is centered on the pilot part 190 of the tool 154 (FIG. 2).This is made possible because the clamp 246 is held open for asufficient length of time and because a wrench member, as shown at 229in my aforesaid patent, is allowed a sufficient degree of movement. Assoon as the blank is centered, however, the clamp member 246 is releasedand clamps the nut blank securely against the face plate. The blank is,therefore, properly centered on the tool and is firmly held in positionso that the centerline of the threads will be perpendicular to the faceof the blank which is against the face plate. The positions of themechanisms shown in FIG. 6 are those immediately after the clamp isreleased by the cam, and would appear at approximately degrees of thecycle. It will be notedthat the cams 238 follow almost exactly thespindle cams 152 between these stations; the only visible deviationbeing at about 330 degrees Where the left hand head moves forwardwithout the rod 229 following. This, however, is wholly unimportant, forthe tool is not held in this head, and the retainer bushing 204 (FIG. 2)has already been positioned as will appear later.

bodiment the tool is so short that it has not been firmly seated in thehead. The tool'is made short so that it will 8 r not break as easilybecause of a long extension and so that it will be more rigid. It willbe recognized, however, that with larger tools it would be feasible andmight be desirable to seat the tool securely in both heads beforestarting the thread cutting operation. As the spindles progress, theright head is fed to the left, forcing the tool through the blank. Thismotion appears between about 30 degrees to just before degrees of thecycle. This is actually the working time of the tool. The cams aredesigned to feed the tool at the proper pitch for the desired thread,and this is one principal reason for the desirability of easyinterchangerof cam segments particularly in view of the different pitchthread systems for a single diameter screw now commonly in use.

During the feeding, the left hand head is substantially dwelling at itsmost extended position. The tool is continuously fed into the head,reversing the rolling of the balls 212 (FIGS. 2 and 4) previouslydescribed, and seating the tool firmly in the left hand head. If the:rod 220 is not properly retracted to the left at the time, the toolwill slide it back against the thrust bearing 232 (FIG. 1). Also duringthis movement, the retainer bushing 204 is moved back to its positionshown in FIG. 4 by the rollingaction of the balls.

At the fourth station (FIG. 8), which corresponds to a point neardegrees in the cycle, the tool is pushed out of the right hand head bythe rod 220 which, in turn, is actuated by the slight rise in the camwhich is provided between 150 and 180 degrees of the cycle. The rise thecam is effective to force the tool out of the grip-of the right handhead and to seat it firmly in the left hand head. At the same time, theretainer bushing 2&4 in the right hand head is positioned by theshoulder 226 on the rod 220.

At this point, too, the left hand head begins to recede from the workholder plates 84 and to carry the tool back with it. As the spindlesprogress to the fifth station (FIG. 9) the tool 154 is completelywithdrawn from the now completed nut. The clamp also is engaged by thecam on the support 248 again and is opened, and the nut is discharged bya pusher bar into an outlet chute.

The next three stations (FIGS. 10-12) show the transfer of the tool fromthe left hand head to the right hand head. This is accomplished whilethe clamp is held open and there is nothing held therein. This motion issimilar to the passing of the tool in the other direction except thatthere is no tool feeding cycle, and therefore the exchange can be mademore quickly. The exchange, in fact, is accomplished while the spindlespass from about 210 to just past 270 degrees in the cycle. In thisspace, the right hand head is substantially at a dwell in its furthestextended position. The left hand head quickly approaches it until thetool is completely inserted into the right hand head. As that headbegins to pull away at approximately 270 degrees, the left hand cam 238continues to push its rod 220 outward until the spindle reaches about285 degrees, thus dislodging the tool from the left hand head andsetting the retainer bushing.

As the spindles pass beyond this point, the right hand head is fullyretracted whereupon the next nut blank is injected and the cyclestartsagain.

From the foregoing description, it can be seen that the spindle cam 150and the push rod cam 238 could be substantially parallel for'all excepta. very small part of the travel of the spindles. Since this is true, itis obvious that the push rod 220 could be carried with spindlesthroughout most of their travel, and 'only short wedge-shaped cams usedWhere necessary, to push the tool out of the respective heads. If suchcams were to be used, the follower could be merely the end of the pushrod which could slide on the cam for a short distance, or the followercould be formed by a ball retained on the end of the rod in a mannerdescribed hereinafter with reference to one of the alternative uses ofthe machine.

During the movement of the spindles longitudinally,

they are also rotated because of the meshing of the pinions 52 with thegear Since the spindles on one side are driven in unison with those onthe opposite side, they are always in position to pass and receive thetool, and both are eifective to drive the tool during the threadingoperation. The preloaded bearings 106, 112 and 118 (and also the bearing166 if the housing 156, 158 of FIGS. 2 and 3 is used) are capable ofboth rotary and longitudinal motion, thus insuring a complete lack ofplay or whip in the spindles. Thus, the spindles are always true, andsince the nut blanks are true, and both tool and blank are securelyheld, the threads will be cut to much closer tolerances than with priormachines using the conventional type hook tap.

It will be recognized that the number of spindles in a machine builtaccording to my invention is not fixed, but that more or fewer could beused. If more spindles were used and the machine driven at the samerotational speed, the output would be proportionately faster. Thus it ispossible with a multi-spindle machine to produce as many as 2500 nutsper minute as compared with present day production with conventionalmachines of from 50-100 nuts per minute. Moreover, the tool is no moreexpensive and perhaps less expensive than present day hook taps and, ifmade of suitable material, will last several times as long measured bythe number of nuts produced per tap. This is true because of thecomplete lack of undesired relative motion between the tap and the nutblank, and because the use of fine fast cutting materials is feasibleonly with such a small tool. Thus my invention makes possible not only agreater production, but the upkeep cost, so far as tools go, isconsiderably less.

While the fundamentally novel features or" the invention have beenillustrated and described in connection with specific embodiments of theinvention, it is believed that these embodiments will enable othersskilled in the art to apply the principles of the invention in formsdeparting from the exemplary embodiments herein, and such departures arecontemplated by the claims.

What is claimed is:

1. In a metal working machine having at least one driven spindle, a tooldriving head comprising a body fixed to said spindle for rotationthereby, said body being adapted to hold and drive a tool having a shankof noncylindrical cross-section, a rigid face plate in said head havinga passage therein adapted to receive and snugly engage in drivingrelation the non-cylindrical shank of such tool, a tool-retainingbushing disposed within said body in axial alignment with said toolpassage, a plurality of anti-friction elements in said tool-retainingbushing for supporting the shank of such tool when the same is inoperative position Within said bushing, and detent means within saidhead adapted to engage a socket in the shank of such tool when the sameis in operative contact with said anti-friction elements for releasablyholding the shank of such tool in operative position in said bushing.

2. In a metal working machine having at least one driven spindle, a tooldriving head comprising a body fixed to said spindle for rotationthereby, said body being adapted to hold and drive a tool having a shankformed with a plurality of axial ribs, a rigid face plate in said headhaving a passage therein adapted to receive and snugly engage in drivingrelation the ribbed shank of such tool, a tool-retaining bushingdisposed within said body in axial alignment with said tool passage, aplurality of anti-friction elements in said tool-retaining bushing forsupporting the shank of such tool when the same is in op erativeposition within said bushing, and detent means within said head adaptedto engage a socket in the shank of such tool when the same is inoperative contact with said anti-friction elements for releasablyholding the shank of such tool in operative position in said bushing.

3. In a metal working machine having at least one driven spindle, a tooldriving head comprising a body fixed to said spindle for rotationthereby, said body being adapted to hold and drive a tool having a shankof noncylindrical cross-section, a rigid face plate in said head havinga passage therein adapted to receive and snugly engage in drivingrelation the non-cylindrical shank of such tool, a tool-retainingbushing disposed within said body in axial alignment with said toolpassage, a plurality of ball bearings in said tool-retaining bushing forsupporting the shank of such tool when the same is in operative positionwithin said bushing, and detent means within said head adapted to engagea socket in the shank of such tool when the same is in operative contactwith said ball bearings for releasably holding the shank of such tool inoperative position in said bushing.

4. In a metal working machine having at least one driven spindle, a tooldriving head comprising a body fixed to said spindle for rotationthereby, said bodv being adapted to hold and drive a tool having a shankof non cylindrical cross-section. a ri id face plate in said head havinga passa e therein adapted to receive and snugly engage in drivinrelation the non-cvlindrical shank of such tool. a tool-retainingbushing disposed within said bodv in axial alignment with said toolpassage. a plurality of anti-friction elements in said tool-retainingbushing for supporting the shank of such tool when the same is inoperative position within said bushing, and spring press detents withinsaid head adapted to engage a socket in the shank of such tool when thesame is in operative contact with said anti-friction elements forreleasably holding the shank of such tool in operative position in saidbushing.

5. In a metal working machine having at least one driven spindle. a to ldriving head comprising a body fixed to said spindle for rotationthereby, said bodv being adapted to hold and drive a tool having a shankof noncylindrical cross-section, a rigid face plate in said head havinga passage therein adapted to receive and snugly engage in drivingrelation the non-cvlindrical shank of such tool, a tool-retainingbushing disposed within said body in axial alignment with said toolpassage, a plurality of pairs of ball bearings in said tool-retainingbushing for supporting the shank of such tool when the same is inoperative position within said bushing, and a plurality of detentswithin said head adapted to engage a slot in the shank of such tool whenthe same is in operative contact with said ball bearings for releasablyholding the shank of such tool in operative position in said bushing.

6. In a metal working machine having at least one driven spindle, a tooldriving head comprising a body fixed to said spindle for rotationthereby, said body being adapted to hold and drive a tool having a shankformed with a plurality of axial ribs, a rigid face plate in said headhaving a passage therein adapted to receive and snugly engage in drivingrelation the ribbed shank of such tool, a tool-retaining bushingdisposed within said body in axial alignment with said tool passage, aplurality of pairs of ball bearings in said tool-retaining bushing forsupporting the shank of such tool when the same is in operative positionwithin said bushing, and a plurality of spring pressed detents withinsaid head adapted to engage a socket in the shank of such tool when thesame is in operative contact with said ball bearings for releasablyholding the shank of a tool in contact with such tool in operativeposition in said bushing.

7. In a metal working machine having at least one driven spindle, a tooldriving head comprising a body adapted to be fixed to said spindle forrotation thereby, said head being adapted to hold and drive a toolhaving a shank of non-cylindrical cross-section and being rearwardlystepped to provide a minor diameter at the end of the shank and a majordiameter inwardly thereof, a rigid wall in said head having a passagetherein adapted to receive and snugly engage in driving relation thenon- .cylindrical shank of such tool, a reciprocating tool-retainingbushing disposed within said body, a fixed supporting surface withinsaid body embracing and maintaining said 1 l tool-retaining bushing inalignment with said tool passage for receiving the stepped shank of suchtool, said fixed supporting surface having a forwardly stepped portionproviding a minor and a major diameter opposite, respectively, the minorand the major diameters of the tool when the latter is in operativeposition within said toolretaining bushing, through sockets in saidretaining bushing over said major and minor diameters of saidsupportingsurface, a first anti-friction element in said socket oversaid major diameter and a second anti-friction element in said socketover said minor diameter adapted to provide a supporting surface tightlyengaging the stepped end of the tool shank when a tool is in operativeposition in said supporting bushing, and means for moving saidtool-retaining bushing and a tool therein forwardly from its operativeposition whereby the minor diameter of the shank registers with saidfirst anti-friction element and said second anti-friction element ismoved into said major diameter of said supporting surface to release thetool from engagement by said elements.

8. In a metal working machine having at least one driven spindle, a tooldriving head comprising a body adapted to be hired to said spindle forrotation thereby, said head being adapted to hold and drive a toolhaving a shank of non-cylindrical cross-section and being rearwardlystepped to provide a minor diameterat'the end of the shank and a majordiameter inwardly thereof, a rigid wall in said head having a passagetherein adapted to receive and snugly engage in driving relation the noncylindrical shank of such tool, a tool-retaining bushing disposed withinsaid-body in alignment with said tool passage for receiving the steppedshank of such tool and mounted therein for reciprocation from anoperative position to a forward tool releasing, position, a forwardlystepped supporting surface for said retaining bushing providing a minorand a major diameter opposite, res'pec tively, the minor and the majordiameters 'of the tool when the latter is in operative position,"through sockets in said retaining bushing over said major and 'minordiameters of said supportingsurface, a first anti-friction element insaid socket over said major diameter and a second anti-friction elementin said socket over said minor diameter adapted to provide a supportingsurface tightly engaging the stepped end of the tool shank when a toolis in operative position in said supporting bushing,

means for reciprocating said tool-retaining bushing and a tool thereinforwardly from its operative position whereby the minor diameter of theshank registers with said first anti-friction element and said secondanti-friction element is moved into said major diameter of saidsupporting surface to release the tool from engagement by said elements,and a detent for holding said supporting bushing in its operativeposition and also in its tool releasing position.

9. In a metal working machine having at least one driven spindle, a tooldriving head comprising a body adapted to be fixed to said spindle forrotation thereby,

said head being adapted to hold and drive a tool having a shank ofnon-cylindrical cross-section and being rearwardly stepped to provide aminor diameter at the end of the shank and a major'dia-meter inwardlythereof, a rigid wall in said head having a passage therein adapted toreceive and snugly engage in driving relation the noncylindrical shankof such tool, a reciprocating tool-retaining bushing disposed withinsaid body, a fixed supporting surface within said body embracing andmaintaining said tool-retaining bushing in alignment with said toolpassage 'for receiving the stepped shank of such'tool, said fixedsupporting surface having a forwardly stepped portion providing a minorand a major diameter opposite, respectively, the minor and the majordiameters of the tool when the latter is in operative position withinsaid toolover said major diameter and a second anti-friction element insaid socket over said minor diameter adapted to provide a supportingsurface tightly engaging the stepped end of the tool shank when a toolis in operative position in said supporting bushing, means for movingsaid toolretaining bushing and a tool therein forwardly from itsoperative position whereby the minor diameter of the shank registerswith said first anti-friction element and said second anti-frictionelement is moved into said major diameter of said supporting surface torelease the tool from engagement by said elements, and a plurality ofspring pressed detents adapted to engage a tool and press it intoengagement with said anti-friction elements, said detents also havingmeans engaging said tool-retaining bushing for holding the same in itsoperative and in its forwardly moved position.

10. In a metal Working machine having at least one driven spindle, atool driving head comprising a body adapted to be fixed to said spindlefor rotation thereby, said head being adapted to hold and drive a toolhaving a shank of non-cylindrical cross-section and being rearwardlystepped to provide a minor diameter at the end of the shank and a majordiameter inwardly thereof, a rigid wall in said head having a passagetherein adapted to receive and snugly engage in driving relation thenoncylindrical shank of such tool, a reciprocating tool-retainingbushing disposed within said body, a fixed supporting surface withinsaid body embracing and maintaining said tool-retaining bushing inalignment with said tool passage for receiving the stepped shank of suchtool, a forwardly stepped portion providing a minor and a major diameteropposite, respectively, the minor and the major diameters of the toolwhen the latter is in operative position within said tool-retainingbushing, through sockets in said retaining bushing over said major andminor diameters of said supporting surface, .a first ball bearing insaid socket over said major diameter and a second ball bearing in saidsocket over said minor diameter adapted to provide a supporting surfacetightly engaging the stepped end of the tool shank when a tool is inoperative position in said supporting bushing, and means for moving saidtoolretaining bushing and a tool therein forwardly from its operativeposition whereby the minor diameter of the shank registers with saidfirst ball bearing and said second ball bearing is moved into said majordiameter of said supporting surface to release the tool from engagementby said elements.

11. In a metal working machine having at least one driven spindle, atool driving head comprising a body adaptedto be fixed to said spindlefor rotation thereby, said head being adapted to hold and drive a toolhaving a shank of non-cylindrical cross-section and being rearwardlystepped to provide a minor diameter at the end of the shank and a majordiameter inwardly thereof, a rigid wall in said head having a passagetherein adapted to receive and snugly engage in driving relation thenoncylindrical shank of such tool, a reciprocating tool-retainingbushing disposed within said body, a fixed supporting surface withinsaid body embracing and maintaining said tool-retaining bushing inalignment with said tool passage for receiving the stepped shank of suchtool, said fixed supporting surface having a forwardly stepped portionproviding a minor and a major diameter opposite, respectively, the minorand the major diameters of the tool when the latter is in operativeposition within said toolretaining bushing, through sockets in saidretaining bushing over said major and minor diameters of said supportingsurface, a first anti-friction element in said socket over said majordiameter and a second anti-friction element in said socket over saidminor diameter adapted to provide a supporting surface tightly engagingthe stepped end of the tool shank when a tool is in operative positionin said supporting bushing, and a sliding rod mounted axially Withinsaid spindle for engaging and moving said tool-retaining bushing and atool therein 13 forwardly from its operative position whereby the minordiameter of the shank registers with said first anti-friction elementand said second anti-friction element is moved into said major diameterof said supporting surface to release the tool from engagement by saidelements.

12. In a metal working machine having at least one driven spindle, atool driving head comprising a body adapted to be fixed to said spindlefor rotation thereby, said head being adapted to hold and drive a toolhaving a shank of non-cylindrical cross-section and being rearwardlystepped to provide a minor diameter at the end of the shank and a majordiameter inwardly thereof, a rigid wall in said head having a passagetherein adapted to receive and snugly engage in driving relation thenoncylindrical shank of such tool, a reciprocating tool-retainingbushing disposed Within said body, a fixed supporting surface withinsaid body embracing and maintaining said tool-retaining bushing inalignment with said tool passage for receiving the stepped shank of suchtool, an axial through passage in said retaining bushing, said fixedsupporting surface having a forwardly stepped portion providing a minorand a major diameter opposite, respectively, the minor and the majordiameters of the tool when the latter is in operative position withinsaid toolretaining bushing, through sockets in said retaining bushingover said major and minor diameters of said supporting surface, a firstanti-friction element in said socket over said major diameter and asecond anti-friction element in said socket over said minor diameteradapted to provide a supporting surface tightly engaging the stepped endof the tool shank when a tool is in operative position in saidsupporting bushing, and a sliding rod mounted axially within saidspindle, said rod having a reduced diameter adapted to enter said axialthrough passage of said retaining bushing and engage the end of a tooltherein and a shoulder adapted to engage said retaining bushing, meansfor reciprocating said rod for moving said tool-retaining bushing and atool therein forwardly from its operative position whereby the minordiameter of the shank registers with said first anti-friction elementand said second anti-friction element is moved into said major diameterof said supporting surface to release the tool from engagement by saidelements.

13. In a metal working machine having at least one driven spindle, atool driving head comprising a body adapted to be fixed to said spindlefor rotation thereby, said head being adapted to hold and drive a toolhaving a shank of fluted cross-section and being rearwardly stepped toprovide a minor diameter at the end of the shank and a major diameterinwardly thereof, a rigid face plate on said head having a passagetherein adapted to receive and snugly engage in driving relation thefluted shank of such tool, a reciprocating tool-retaining bushingdisposed within said body, a fixed supporting surface within said bodyembracing and maintaining said toolretaining bushing in alignment withsaid tool passage for receiving the stepped shank of such tool, fixedsupporting surface having a forwardly stepped portion providing a minorand a major diameter opposite, respectively, the minor and the majordiameters of the tool when the latter is in operative position withinsaid tool-retaining bushing, through sockets in said retaining bushingover said major and minor diameters of said supporting surface, a firstanti-friction element in said socket over said major diameter and asecond anti-friction element in said socket over said minor diameteradapted to provide a supporting surface tightly engaging the stepped endof the tool shank when a tool is in operative position in saidsupporting bushing, and means for moving said toolretaining bushing anda tool therein forwardly from its operative position whereby the minordiameter of the shank registers with said first anti-friction elementand said second anti-friction element is moved into said major diameterof said supporting surface to release the tool from engagement by saidelements.

References Cited in the file of this patent UNlTED STATES PATENTS Re14,086 Daniels Mar. 14, 1916 437,713 Newbury Oct. 7, 1890 1,458,300Jarvis June 12, 1923 1,538,670 Stanley May 19, 1925 1,747,418 BishopFeb. 18, 1930 2,388,779 Boehmler Nov. 13, 1945 2,579,081 Koch Dec. 18,1951 FOREIGN PATENTS 556,681 Great Britain Oct. 15, 1943

